Operating Segments - Reconciliation of Operating Profit (Loss) from Segments to Consolidated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	$ 370,036	$ 267,196	$ 187,338
Cost of revenue	258,216	184,452	138,492
Gross profit	111,820	82,744	48,846
Operating expenses	127,792	105,528	79,135
Net income (loss)	(15,002)	(22,526)	(30,236)
Real Estate
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	351,570	260,383	181,446
Cost of revenue	237,832	176,408	131,522
Gross profit	113,738	83,975	49,924
Other Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	18,466	6,813	5,892
Cost of revenue	20,384	8,044	6,970
Gross profit	$ (1,918)	$ (1,231)	$ (1,078)